The oxide transistor technology as a technical hotspot at the present stage has the characteristics of high mobility and good uniformity etc. However, when manufacturing an array substrate comprising the oxide transistor, dry etching will be performed to an inter-layer insulator so as to form a via hole for connecting a semiconductor layer, and form a source electrode and a drain electrode coupled with the semiconductor layer through the via hole. At present, there are mainly the following several ways to improve the resistance generated by contact of the source electrode or the drain electrode with the semiconductor layer: changing the size of the via hole; changing the shape of the via hole; increasing the number of the via holes; inserting a transition layer on the semiconductor layer; changing the material of the source electrode or the drain electrode.
However, for the case where the design scheme of the via hole in the array substrate has been determined, the resistance cannot be improved by the first three methods as stated above. The method of inserting a transition layer not only will increase the risk of influencing the yield, but also will increase the production cost accordingly. As for the improving method of changing the material of the source electrode or the drain electrode, wiring of a medium or large size display device driven by AMOLED generally uses Al or Cu, hence, there are extremely few materials for selection and change. It can be seen that, the prior art fails to make improvement to the resistance generated by contact of the source electrode or the drain electrode with the semiconductor layer in the event that the design scheme of the via hole and the material of the source electrode or the drain electrode have both been determined.